acpi/Kconfig: move \_SB scope out of ACPI_CPU_STRING

In ACPI 1.0 the processor objects were inside the \_PR scope, but since
ACPI 2.0 the \_SB scope can be used for that. Outside of coreboot some
firmwares still used the \_PR scope for a while for legacy ACPI 1.0 OS
compatibility, but apart from that the \_PR scope is deprecated.
coreboot already uses the \_SB scope for the processor devices
everywhere, so move the \_SB scope out of the ACPI_CPU_STRING to the
format string inside the 3 snprintf statements that use the
ACPI_CPU_STRING.

Signed-off-by: Felix Held <felix-coreboot@felixheld.de>
Suggested-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Change-Id: I76f18594a3a623b437a163c270547d3e9618c31a
Reviewed-on: https://review.coreboot.org/c/coreboot/+/75167
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>
Reviewed-by: Tim Wawrzynczak <inforichland@gmail.com>
Reviewed-by: Matt DeVillier <matt.devillier@amd.corp-partner.google.com>
Reviewed-by: Fred Reitberger <reitbergerfred@gmail.com>
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>

src/acpi/Kconfig

@@ -8,13 +8,11 @@ config ACPI_AMD_HARDWARE_SLEEP_VALUES
 
 config ACPI_CPU_STRING
 	string
-	default "\\_SB.CP%02X"
+	default "CP%02X"
 	depends on HAVE_ACPI_TABLES
 	help
 	  Specifies the ACPI name format string used by the acpigen
-	  function to generate the processor scope. Default is \_SB.CPxx.
-	  Note that you need to escape the '\' character in the string.
-	  The resulting string will be truncated to at most 15 chars.
+	  function to generate the processor scope. Default is CPxx.
 
 config ACPI_HAVE_PCAT_8259
 	def_bool y if !ACPI_NO_PCAT_8259

src/acpi/acpigen.c

@@ -391,7 +391,7 @@ void acpigen_set_package_element_namestr(const char *package, unsigned int eleme
 void acpigen_write_processor_namestring(unsigned int cpu_index)
 {
 	char buffer[16];
-	snprintf(buffer, sizeof(buffer), CONFIG_ACPI_CPU_STRING, cpu_index);
+	snprintf(buffer, sizeof(buffer), "\\_SB." CONFIG_ACPI_CPU_STRING, cpu_index);
 	acpigen_emit_namestring(buffer);
 }
 
@@ -1939,7 +1939,8 @@ void acpigen_write_CPPC_package(const struct cppc_config *config)
 void acpigen_write_CPPC_method(void)
 {
 	char pscope[16];
-	snprintf(pscope, sizeof(pscope), CONFIG_ACPI_CPU_STRING "." CPPC_PACKAGE_NAME, 0);
+	snprintf(pscope, sizeof(pscope),
+		 "\\_SB." CONFIG_ACPI_CPU_STRING "." CPPC_PACKAGE_NAME, 0);
 
 	acpigen_write_method("_CPC", 0);
 	acpigen_emit_byte(RETURN_OP);

src/cpu/amd/pi/00730F01/Kconfig

@@ -10,6 +10,6 @@ if CPU_AMD_PI_00730F01
 
 config ACPI_CPU_STRING
 	string
-	default "\\_SB.P%03d"
+	default "P%03d"
 
 endif # CPU_AMD_PI_00730F01

src/soc/amd/common/block/cpu/Kconfig

@@ -35,7 +35,7 @@ config CBFS_CACHE_SIZE
 
 config ACPI_CPU_STRING
 	string
-	default "\\_SB.C%03d"
+	default "C%03d"
 
 endif # SOC_AMD_COMMON_BLOCK_NONCAR
 

src/soc/amd/stoneyridge/Kconfig

@@ -268,7 +268,7 @@ config SMM_MODULE_STACK_SIZE
 
 config ACPI_CPU_STRING
 	string
-	default "\\_SB.P%03d"
+	default "P%03d"
 
 config ACPI_SSDT_PSD_INDEPENDENT
 	default n

src/soc/intel/common/block/acpi/cpu_hybrid.c

@@ -158,7 +158,7 @@ void acpigen_write_CPPC_hybrid_method(s32 core_id)
 		snprintf(pkg_path, sizeof(pkg_path), CPPC_PACKAGE_NAME, 0);
 	else
 		snprintf(pkg_path, sizeof(pkg_path),
-			 CONFIG_ACPI_CPU_STRING "." CPPC_PACKAGE_NAME, 0);
+			 "\\_SB." CONFIG_ACPI_CPU_STRING "." CPPC_PACKAGE_NAME, 0);
 
 	acpigen_write_method("_CPC", 0);
 

src/soc/intel/xeon_sp/spr/Kconfig

@@ -25,7 +25,7 @@ config MAX_CPUS
 
 config ACPI_CPU_STRING
 	string
-	default "\\_SB.C%03X"
+	default "C%03X"
 
 config SIPI_FINAL_TIMEOUT
 	int